What's the difference between these two TVs?

[unplanned bacon]

http://www.pcworld.co.uk/gbuk/tv-dvd-audio/televisions/televisions/samsung-ue40ku6470-smart-4k-ultra-hd-hdr-40-led-tv-10146920-pdt.html

http://www.pcworld.co.uk/gbuk/tv-dvd-audio/televisions/televisions/samsung-ue40ku6400-smart-4k-ultra-hd-hdr-40-led-tv-10146895-pdt.html

Samsung have released a million different products with barely any difference between them and gave them weird model numbers so it's not exactly clear which is better

 

[Eximo]

6470 offers voice control, other than that I would guess identical.